US Bridges

County Road 103 over Middle St. Vrain Creek

Fair

Boulder County, Colorado · 100 Feet S of State High · Structure no. BC-103-4.0-MSV

Built
1927
98 years old
Condition
Fair
inspected January 2025
Type
Tee Beam
Concrete
Length
35 ft
1 main span
Daily traffic
56
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 103 over Middle St. Vrain Creek is a concrete tee beam carrying County Road 103 over Middle St. Vrain Creek in Boulder County, Colorado. It was built in 1927, so it is 98 years old, older than the Colorado average of 42.2 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 56 vehicles a day, roughly 20% of them trucks, projected to reach 67 by 2043. The structure is 35 ft (10.7 m) long and 23 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesCounty Road 103
CrossesMiddle St. Vrain Creek
Location100 Feet S of State High
RouteCounty Highway 0
CountyBoulder County
StateColorado
Coordinates40.13617, -105.49208
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJanuary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating57.2 US tons
Inventory rating34.3 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length35 ft (10.7 m)
Longest span29 ft (8.9 m)
Deck width23 ft (7.1 m)
Roadway width20 ft (6.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic56 (2023)
Projected traffic67 by 2043
Trucks20%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was County Road 103 over Middle St. Vrain Creek built?

It was built in 1927, making it 98 years old in 2025.

What condition is County Road 103 over Middle St. Vrain Creek in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in January 2025.

How much traffic does County Road 103 over Middle St. Vrain Creek carry?

About 56 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is County Road 103 over Middle St. Vrain Creek?

The structure is 35 ft (10.7 m) long with a longest span of 29 ft (8.9 m) and a deck 23 ft wide.

Who owns County Road 103 over Middle St. Vrain Creek?

It is owned by the County Highway Agency.